In a RAID technology, data may be directly stored and read on a physical disk. When the physical disk fails or is in a half-life state, reconstruction may be started to restore data in the failed physical disk or the to-be-failed physical disk to a hot spare disk, and a logic unit number (LUN) of the physical disk is restored to a normal state, which ensures reliability of a whole storage system.
In the existing RAID, if a physical disk fails, data is read from other physical disks of the RAID. Exclusive-OR is performed on the read data and then the data is written into a hot spare disk. This method has a problem: data from multiple physical disks all needs to be written into one hot spare disk, so a written speed of the hot spare disk becomes a bottleneck, thereby resulting in a low RAID reconstruction speed.